Sonoma Valley Groundwater

    Home | Basin Advisory Panel | Documents | Meetings | Monitoring


    What's New


    Sonoma Valley Groundwater Management Program

    Sonoma Valley Groundwater Management Program - logoGroundwater resources have long played a significant role in the development, growth and sustainability of the Sonoma Valley, with more than half the water demand in a given year met by local groundwater resources. With increasing local demands, assuring sustainable groundwater supplies in the Sonoma Valley may be difficult unless appropriate actions are taken in the near future.  

    These groundwater resources are relied upon by rural and urban residents, vineyards and wineries, dairies, and other businesses and also support the rich ecosystems present in Sonoma Valley. Assuring sustainable groundwater supplies in the Sonoma Valley is critical to the environmental health and economic vitality of the Basin. In recognition of the importance of local groundwater resources, local agencies and stakeholders have funded and supported technical studies and voluntary groundwater management programs that provide a strong technical and institutional foundation to build upon under SGMA. The USGS completed studies and modeling of the basin in 2006, and basin stakeholders engaged in a voluntary Groundwater Management Program between 2007 and 2017. Key information, tools and outcomes from these previous groundwater management planning activities include:

    • Technical information on the Basin hydrology, hydrogeologic framework, water chemistry and source, surface water and groundwater interaction monitoring, and records of groundwater levels, including historical trends and documentation of two depressions in southern Sonoma Valley.
    • Development of a MODFLOW groundwater flow model of surface water and groundwater systems in the Basin and contributing watershed area.
    • Engagement of local stakeholders in local groundwater planning and management.

    Further information and details on these studies and voluntary management work are provided in the following key studies that document the conditions of the Sonoma Valley groundwater basin:

    In 2017, as the Sonoma Valley Groundwater Sustainability Agency was forming and beginning to assume management responsibilities for the Sonoma Valley Groundwater Subbasin under the Sustainable Groundwater Management Act (SGMA), the Basin Advisory Panel and Technical Advisory Committee developed the Insights and Recommendations, Sonoma Valley Groundwater Conditions and Management document.  In addition to providing recommendations for consideration by the GSA, the document also includes an attachment that summarizes the current understanding of groundwater conditions in Sonoma Valley.


    Sustainable Groundwater Management Act

    In September 2014, Governor Brown signed legislation requiring that California’s critical groundwater resources be sustainably managed by local agencies. The Sustainable Groundwater Management Act (SGMA) gives local agencies (cities, counties and water districts) powers to sustainably manage groundwater over the long-term, and requires Groundwater Sustainability Agencies (GSAs) be formed and Groundwater Sustainability Plans (GSPs) be developed for medium- and high-priority groundwater basins.  The Sonoma Valley groundwater sub-basin (as defined in DWR’s Bulletin 118 and shown on Figure 1-1) is currently identified as a medium priority basin and is, therefore, subject to the requirements of SGMA. 

    In May 2018, DWR proposed elevating the Sonoma Valley basin to a high priority basin. Public comment is open until August 20th, 2018 with final prioritization in mid-October. The proposed change is not expected to have any immediate impact on the development of the Groundwater Sustainability Plan or other GSA activities, as medium and high priority basins are subject to identical requirements and timelines under SGMA. Public comment on the proposed reprioritization is open until August 20th, 2018 with final prioritization in mid-October. View a map of these groundwater basins on the Department of Water Resources website.

    The Sonoma Valley Groundwater Sustainability Agency is developing a new groundwater sustainability plan, which must be completed by 2022. The existing GMP forms a strong foundation upon which to build in the development of the new GSP.

    For further information on the new groundwater law and SGMA activities in Sonoma County, visit


    Important Info & Documents


    Past Presentations


    Contact Information

    Marcus Trotta
    Sonoma County Water Agency
    (707) 547-1978